The present invention relates to a fastener driving tool, or like apparatus, comprising a barrel adapted to receive a fastener intended to be driven in translation in the barrel under the action of the combustion gases of a propellant charge, a breech in which a striker is slidingly mounted, a loader carrying propellant charges, between the barrel and the breech, provided with orifices for receiving the propellant charges, and means for driving the loader in displacement.
Patent DT-AS No. 2,031,994 describes a tool of this type, in which the loader is a loader in the form of an annular disc mounted to rotate on itself, of which the orifices for receiving the propellant charges are angularly spaced apart in regular manner, and which is provided with peripheral teeth adapted to cooperate with a drive lever which may be actuated by a cocking lever in order, during cocking of the tool, to drive the loader in rotation over an angular distance equal to that separating two adjacent orifices and thus to present a fresh charge opposite the striker of the breech.
The adoption of such a loader follows from the requirement that a maximum of propellant charges be disposed in a minimum of space. The orifices for receiving the charges are therefore very close to one another.
With such a tool, in which the charges are therefore very close to one another, upon firing of one of these charges, the two charges adjacent thereto may well be fired also by sympathetic ignition, via the loader itself which constitutes a support of propagation of the mechanical stress created by the firing of the charge in question.
The fact of spacing the charge-receiving orifices apart on the loader would not constitute a satisfactory solution since this would be to the detriment of the quantity of charges available on the loader or of the dimensions of this loader.
It is an object of the present invention to eliminate or considerably reduce the risk of firing, by sympathetic ignition, the propellant charges disposed on the loader of a tool of the above mentioned type.
To this end, the present invention relates to a tool of this type, characterized in that the loader comprises means adapted to form an obstacle to the propagation of the mechanical stress created by the firing of a propellant charge.
Thanks to the obstacles according to the invention, the propagation of the stress is considerably inhibited, failing complete stoppage; and when said stress reaches one or the other of the adjacent charges, its level is such that the risk of sympathetic ignition is considerably reduced, if not zero.
Naturally, the scope of this invention is not intended to be limited to loaders mounted to rotate on themselves.
In a preferred embodiment of the invention, the loader comprises small, sympathetic ignition inhibiting orifices adjacent the charge-receiving orifices, at least one adjacent each of the charge-receiving orifices, advantageously arranged outside the line of the centers of two adjacent charge-receiving orifices, on one side or the other.
The invention is, of course, applicable both to direct firing tools and to indirect firing piston tools. It will be recalled that, in tools of the latter type, a fastener is driven therein under the action of the combustion gases via a piston mounted to slide in the barrel.